Gear-cutting machine



Patented Apr. 12, 1921. 6 SHEETS-SHEET l.

.D7/ventola F. LJUNGSTRM.

GEAH CUTTING MACHINE.

APPLICATION FILED MAYs,192o.

t l l F. LIUNGSTFIM.

GEAR CUTTING MACHINE.

APPLICATION FILED MAY 8, 1920.

Patented Ap1i12, 1921.

F. LJUNGSTHM.

GEAR CUTTING MACHINE.

APPLICATION FILED MAY a. 1920.

Patented Apr. 12, 1921.

6 SHEETS-SHEET 3.

I, nu

v tbox m95 Patented Apr. 12, 1921.

6 SHEETS-SHEET 4.

F.1 JUNGSTRM- GEAR CUTTING MACHINE. APPLICATION FILED MAY a, 1920.

1,374,460. Patented Apr. 12, 1921.v

F. LJUNGSTRM.

GEAR CUTTING MACHINE.

APPLICATION man MAY s. 1920.

Patented Apr. 12, 1921.

, 6 SHEETS--SHEET 6.

15 chines as *l UNITED STATES PATENT OFF-ICE.,

aannam LJUNesrnm, or nnEvIx, LIDINGN, SWEDEN," AssIeNon. To AKTIE-iaoLAeE'r LJUNGsTnoM ANGTURBIN, or srocxnoniu, SWEDEN, al coieroiaii-ATION.

I enanfctrr'rine MACHINE.

Specication of-Letters Patent.

Application filed May 8, 1920. Serial No. 379,897.

' cation.

The present invention relates yto improve- 10 ments in gear cuttingmachines and its object is to produce more accurate work and.

secure uniform movement of. the various rotating parts of the machine.

Owing to defects in the gear cutting. ma-

heretofore .u sed certain errors are apt to occur in milling some ofwhich errors are produced by defective gears, etc., constituting partsof the machine, whereas other errors are caused the rotating tablelacking an angular velocity of mathematical constancy relatively to theangular velocity of the remainin parts, for instance that of the cutterar or. Both these reasons may coact, or

they may he independent of each other, and

they result in irregularities of the form of the teeth and tooth spaces.Supposing that the rotating table is driven by means o f a toothedgearing, one of the gears being defective, so that a tooth en ages the`following gear too soon, this wi l result in an increased angularvelocity of the table, and, consequently, a faulty or a misplaced toothis roduced by the machine. rE

he presentinvention has for its purpose to obviate these drawbacks, andconsists in connecting the rotating table, the cutter arbor or othermoving parts of the gear cutting machine to a, gyrating mass, forinstance a iiy-wheel, by means of a Jfriction gearing. In such anarrangement, the highspeed parts of the friction gearing may have aseparate driving means. In this way a constant angular velocity of thetable is enforced, the movement of the table bein dependent on a gyatingmass connecte thereto, such gyrating mass evidently tending to retain aconstant angular velocity. If the cutter arbor or other movable partsare also connected to the gyrating mass, said parts will also obtain,the same angular velocities with substantially mathematical exactness,and thus the gear cutting machine will produce teeth which aresubstantially the gear teeth,

`in the Work-piece. plicable to those parts of the gearing of themathematically correct. Then the rotating parts connected with a ratingmass will Patented Apr. 12, 1921."

not always have the angu ar velocity which the. driving means tends toimpart thereto. This difference in speed is evidenced by an increasedpressure on thel defective parts of the gear cutting machine, whichadmits of the r1 ht speed through the resiliency thereof. n this 'waythe ear cutting machine will a ct very exacty' owing to the mutualwearing and grinding action effected by its several members.

By the employment of gear wheels, produced in a gear cutting machineaccording te the invention, in other gear cutting machine according tothe invention, the final result will obviousl be still better, and inthis way teeth will nally be obtained which are of an absolutemathematical exactness. e The movable parts of the machine should not beconnected with a gyrating mass by means of a toothed gearing, as errorsoccurring in the sult in non-uni ormity of the tooth-shapes This isparticularly apiy-wheel which are driven at the lowest speed. However,the hi h-speed part of the gearing may consist o gear wheels, as a faultin the same is not very perceptible,

one Wheel, perhaps, making one or more revolutions each time a tooth ofthe workpiece is going past the cutter.

Consequently, the rotatin Vparts of the gear cutting machine shoul beconnected wholly or partly with the gyrating mass by means offriction-gearings comprisin cylindrical or conical wheels or rollers roling on each other. Rollers or wheels which are mathematically-correctmay be easilyprocured, and thus a gearing of the said type mzy beregarded as being free from defects.

the 'accom anying drawings, four embodiments of t e invention are shownby way of example in Figures l and 2, 3 and 4, 5 and 6 and in Fig.respectively, Fig. 8 being a diagrammatical illustration of one form ofa detail arrangement.

. Figs. 1 and 2 show an embodiment in which the table is connected totwo ilywheels 2 'and 3 by means of a friction-gearin the said fly-wheelsbeing located on eit er side ofthe table. The periphery of the-latter isprovided with a rough'ened or ear wheels would then re`' frictionsurface, s'o as to drive the rollers 4 and 5 attached to the same shafts6 and 7 as the larger friction wheels 8 and 9 which in turn drive therollers '12 and 13 secured to the fly-wheel shafts 10 and 11.Consequently, the motion of the table depends on the movements of thebalance wheels 2 and 3., Preferably, the frictiongearing is mounted inball bearings 14 so as to reduce the ower 4consumed for driving thegearing. he table 1 is driven in known manner by means of a worm 21 andaworm wheel.

In the embodiment according to Figs. 3 and 4, the worm 21 serving todrive the table isconnected with the fly-wheel 2. This spindle has agreater Speed of rotation than the table, and thus a smaller ratio ofgearing may be selected than in the embodiment according to Figs. 1 and2, in order to obtain a suiiicient ener of movement in the fly-wheel 2.The spmdle 21 is provided at one end with a friction wheel 8 drivin thesmaller roller 12 secured to the same s aft 10 as the fly-wheel'2. Theiiywheel, which attains a comparatively high speed and has a constantangular velocity, consequently imparts a constant angular 'velocity tothe screw-spindle. In case the speed of the table is also maintainedconstant, as shown in Figs. 1 and 2, the worm and worm-wheel willgradually obtain a constant speed owing to the mutual grinding andwearing action effected by sald members.

Figs. .5 and 6 also illustratefan embodi-I ment in which the cutterarbor is connected with a fly-wheel. The shaft 32, to which the cutter31 is secured, is provided for instance at one end or both ends with afriction wheel 33 which in this case referably transmits the motion tothe 'fly-w eel 34 by means of two arallel intermediate shafts 35 and 36Whi'c are also provided with friction wheels 37 and 38, and 39 and 40,wheels 37 and 39 being of a smaller size and running in con-- teethproduced would be substantially mathwill be substantially accurate.

. ematically exact.

On account of the construction and the movement of the cutter, a slighterror in it will be gradually eliminated, and by reason of this a gearWheel cut in a machine according to the invention Obviously the y-wheelmay be stepped up to a much greater speed 5 an embodiment of thischaracter is shown 1n Fig. 7. Here the wheel 34, which in the embodimentaccording to Figs. 5 and 6 served as a balance wheel, 1s arranged as awheel in the gearing 70 and connected with the balance wheel 51 in theSame manner as the wheel 33 is connected With the balance wheel 34.inFigs. 5 and 6. To reduce the power taken from the cutter arbor to drivethe earing and the balance wheel, an intermediate shaft in the gearingmay be preferabl provided with another driving device. 1` n thisembodiment, the intermediate shaft 52 is connected vdirectly to an'electric motor 53. The last 8o part of the gearing may withoutinconvenience consist of gear Wheels, but in such case.these gear Wheelswill have to be as faultless as possible. In this case, too, the gearingshould be mounted in'ball-bearings, 85 in order that the powerconsumption will be as small as possible.

Fig. 8 shows an embodiment of a starting and driving means for thebalance wheel previously denoted by the numeral 3. In A this case thearrangement consists of a balance wheel 54 surrounded by a rotating.casing 55 driven by a separate motor or by means of a pulley 56. Thebalance wheel is preferably mounted in the casing by means I of a thrustbearing 57, and the casing is supported by the bearing 58 in the frame59.

he casing 1s provided with a shaft 60 connected to any driving motor.When starting.l the equalizer, the casing is brought in motionslmultaneously as a liquid, for instance oil, is pressed into the casingthrough the inlet channel 61 in the shaft 60. This inlet channel 61mustbe so dimensioned as to y permit of more oil being forcedtherethrough 1,05 than emitted through the apertures 62 in vthe casing55. In this Way a soft starting 'of the balance wheel 54 is obtained. As

soon as the balance wheel has attained the desired speed, the inletchannel 61 is shut 110 oif so that the liquid will ow out ofthe casingthrough the apertures 62 and an air l stratum be produced between theinner walls of the casing and the balance wheel. This stratum hasthesame properties as the oil, v

but, in a lesser degree, the friction thereof tending to keep the casingand the balanceV wheel at the samespeeds. Thus, the casing is driven atAnearly the same speed as the balance wheel by means of the drivingmotor, and is conducive to the retainment of a constant speed of thebalance wheel.

As evidently the movable parts of the gear cuttingmachme will in thisway gradually obtain a constant speed owing to the mutual grinding andwearlng action effected by said members, the said machine conse uentlyacquires ever increasing accuracy wfiien in use.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is 1. In -a gear cutting machine, the combination with theoperatinggmechanism and a 5 gyrating mess,` of a, connection between theoperating mechanism and -sai'd mass consist-v ing of a friction gearingadapted' to transmit an increased speedtQ and mass.

2. A combination as said `connection defined in Claim 1,111

which the parts ofuthengearing possessing the increased speed areconnected with sepas- Witnesses:

O. H. BERGROLK, INEz BoNEssoN.

FREDRIK LJUNGSTRM. Y

